1. Field of the Invention
One embodiment of the present invention relates to semiconductor devices, display devices, and the like.
2. Description of the Related Art
The increase in size of display devices such as liquid crystal display devices and EL display devices promotes the development of display devices with higher added value. In particular, techniques by which a driver circuit in a display device is composed of only transistors having the same conductivity type have been actively developed (see Patent Document 1).
FIG. 16 illustrates a driver circuit disclosed in Patent Document 1. The driver circuit in Patent Document 1 includes transistors M1 to M7. When a signal GOUT[N−1] goes high, the transistor M3 is turned on. Thus, a voltage VON is supplied to a gate of the transistor M1, so that the gate potential of the transistor M1 starts to rise. Since the gate potential of the transistor M1 rises gradually, a potential difference between a gate and source (hereinafter also referred to as Vgs) of the transistor M3 decreases gradually. Then, Vgs of the transistor M3 becomes the threshold voltage of the transistor M3, and the transistor M3 is turned off.